Earth may have 'hairy' dark matter, says NASA

Updated: Tuesday, November 24, 2015, 11:51 [IST]

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Washington, Nov 24: There may be long filaments of dark matter or "hair" on our Earth, suggests new research, adding further study is needed to unlock the mysteries of the nature of dark matter on Blue Marble.

Dark matter is an invisible, mysterious substance that makes up about 27 percent of all matter and energy in the universe.

The regular matter, which makes up everything we can see around us, is only five percent of the universe.

The rest is dark energy, a strange phenomenon associated with the acceleration of our expanding universe.

According to previous calculations and simulations performed in the last decade, dark matter forms "fine-grained streams" of particles that move at the same velocity and orbit galaxies such as ours.

"A stream can be much larger than the solar system itself and there are many different streams crisscrossing our galactic neighbourhood," said Gary Prezeau from NASA's Jet Propulsion Laboratory in Pasadena, California.

He found that when a dark matter stream goes through a planet, the stream particles focus into an ultra-dense filament or "hair" of dark matter.

In fact, there should be many such hairs sprouting from the Earth.

A stream of ordinary matter would not go through the Earth and out the other side. But from the point of view of dark matter, the Earth is no obstacle.

According to Prézeau's simulations, the Earth's gravity would focus and bend the stream of dark matter particles into a narrow, dense hair.

Hairs emerging from planets have both "roots," the densest concentration of dark matter particles in the hair, and "tips" where the hair ends.

When particles of a dark matter stream pass through the Earth's core, they focus at the "root" of a hair, where the density of the particles is about a billion times more than average.

The root of such a hair should be around one million km away from the surface, or twice as far as the moon.

The stream particles that graze the Earth's surface will form the tip of the hair, about twice as far from the Earth as the hair's root.

"If we could pinpoint the location of the root of these hairs, we could potentially send a probe there and get a bonanza of data about dark matter," Prezeau noted.

A stream passing through Jupiter's core would produce even denser roots: almost one trillion times denser than the original stream, according to Prézeau's simulations.

"Dark matter has eluded all attempts at direct detection for over 30 years. The roots of dark matter hairs would be an attractive place to look, given how dense they are thought to be," added Charles Lawrence, chief scientist for JPL.